Neo-Thomism

Neo-Thomism, also known as neo-scholasticism, is a revival, further development, and refinement of medieval scholasticism, especially the thought of Thomas Aquinas. Its main venue has been in Catholic philosophy, beginning in the second half of the 19th century. In the 19th century, there was a renewal of interest among Catholic thinkers of scholastic methodology and thought, a response to modernism, the thought of such philosophers such as Rene Descartes, Immanuel Kant, and Georg Wilhelm Friedrich Hegel, which Catholics viewed as hostile to Christian doctrine. Modernism was attacked by Pope Pius X in 1907, calling it "the sum of all heresies". Given that modernism was perceived as the enemy of Catholic thought in the late 19th-early 20th centuries, the desire to go back to, and be inspired by, the thought of Thomas Aquinas grew. In its early days, neo-Thomist thought had attacked three essential common threads of thought that it attacked: the belief that dogmas are not changeless, the belief that revelation did not end with the death of the last apostle; and the historical-critical method of analyzing religious thought. These were dangers to Catholic teaching, and the thoughts could only be overcome through returning to the faithful philosophy of Thomism. Neo-Thomism flourished with particular vigor in Italy before spreading to the rest of Catholic Europe, with some of its leading thinkers being French-speakers in France, Switzerland, and Belgium, as well as Germany, Spain, Austria-Hungary, the United States, Latin America, and other parts of the world.

Papal support
Papal support for neo-Thomism began in the middle of the 19th century under Pope Pius IX, the longest-reigning Pope. His pontificate had heralded a move away from modern forms of thought; his successor Pope Leo XIII showed some more openness to the modern world, but in an encyclical issued in 1879, he set out the principles of neo-scholasticism and pointedly recommended the study of Aquinas and the restoration of Christian philosophy to Thomism's spirit. Leo XIII ordered the Pontifical Academy of St. Thomas Aquinas to publish his complete works in their definitive critical edition, doing much to support an increased study of Aquinas and the proliferation of neo-Thomist thought, especially in contrast to Kant.

Major principles
Neo-Thomism's main principles were that God is pure actuality and absolute perfection, and that he was therefore substantially distinct (by his very essence and nature) from every other thing, certainly from every other finite thing. God alone could create and preserve beings other than himself, and his knowledge is infinite. Whatever exists is itself an individual, with anything that is self-subsisting being an incommunicable substance. To the core of that incommunicable, self-subsisting reality, are then added other realities (accidents) such as size, form, roughness, etc. The nature of each substance is fixed and determined, giving it stability and permanence. To the static dimension of its existence, the concept of actuality and potentiality are applied, complimenting the stability of substance with the possibilities of change. Key to understanding motion change is the theory of matter and form; matter is potentiality, while form is actuality. The theory of matter and form is crucial to understanding the substantial changes undergone by bodies. What constitutes the essence of a concrete being is a union of matter and form; this essence is then endowed with existence and brought from potentiality into actuality. Throughout all change and becoming, there is a rhythm of finality, with all substances in the universe converging towards an end in accordance with the maxim of Aristotle, that the final cause or the end of purpose is the "cause of all causes"; that the universe is ends-driven. This end purpose is known by God. As a compound of body and soul, man puts forth activities of a higher order. Through his senses, man perceives concrete objects; through his senses, he knows the abstract and universal. All our intellectual activity rests on sensory function, but through the active intellect or agent intellect, abstract representations of sensible objects are provided, hence what is characteristic of an idea is its immateriality. This is based upon the spiritual argument of the immortality of the soul. For example, all oak trees are identical with respect to certain constituent elements. Considering this likeness, humans group all oak trees into one species and view their common characteristics. All oak trees are a common species; as trees, they are a common genus with other trees. Each, in its nature, is fixed and determined. In their essences, they are stable and do not change. What explains change is supplied by the concepts of actuality and principality. Whatsoever changes is, for that very reason, something finite. The oak tree will die, but, from its decaying trunk, other substances will come forth. The coming forth of other substances from the trunk would constitute a substantial change. The theory of matter and form is one of interpreting the substantial changes that bodies undergo. From particular oak trees, we strip away everything that makes each particular so that we end up with the general concept (a universal) of the oak tree's species. From our sensory function, our intellect then abstracts the general from the particular. Our active intellect is able to create abstract representations of sensible objects so that we are left with something entirely immaterial - an idea. The seat of our ideas, the soul, is therefore immortal; here too is the foundation of logic and epistemology. Above our happiness is a supernatural happiness, where philosophy ends and theology begins; the natural realm is the domain of philosophy, while the supernatural realm is the proper domain of theological inquiry.